The invention relates to a gas bag arrangement for a vehicle occupant restraint system, with a gas bag inflatable by a gas generator to protect a vehicle occupant, whose envelope defines an interior space of the gas bag that can be filled with gas, with a vent opening through which gas can flow out of the gas bag, and with a device for controlling the outlet cross-section of the vent opening, which comprises at least one covering part with which the vent opening can be covered, in order to at least partly close the same, and which furthermore comprises an actuating mechanism which interacts with the covering part, in order to vary the outlet cross-section of the vent opening, wherein the actuating mechanism includes an additional gas source (different from the gas generator) and an element different from the gas bag and inflatable by means of the gas source, which during inflation interacts with the covering part such that it effects a change in the outlet cross-section of the vent opening.
Such gas bag arrangement (also referred to as airbag module) is known for example from WO 2011/157631, whose inflatable element is provided for covering a vent opening in a gas bag and by releasable connections, preferably in the form of tear seams, is attached to the edge regions of the gas bag surrounding the vent opening. After destruction of the tear seams, parts of the inflatable element clear the vent opening or close the same, and thus in the case of a crash adapt the restraint of the gas bag to certain sensed constraints (vehicle speed, occupant characteristics, seating position, etc.). Independent of the design, the size of the inflatable element must be matched with the size of the associated vent opening. Adapted to various conditions of use, such as vehicle type, kind of airbag module (driver, passenger, side airbag module, etc.), size of the gas bag or characteristic of the gas generator, the vent openings have different shapes and sizes. This means that the dimensioning (blanks, seam contours, fillable volume) of the inflatable elements also is changed correspondingly. Especially the design of the releasable connections (tear seams) requires a high development effort, since the initiated, desired release should be effected safely and quickly in a broad temperature range, so that in the case of a crash the restraint of the gas bag can be adapted to the above-mentioned constraints in good time.